In the three species Dicentrarchus labrax, Sparus auratus , and Anguilla anguilla an artificial feeding (dry pellets) disturbs liver cells as revealed at ultrastructural level. In hepatocytes, anomalies consist of lipids storage (liposomes) considered as deviation in fatty acids metabolism. Moreover are observed cellular alterations (mitochondrial vacuolization, nuclear pycnosis) related to degenerative process. It is of great interest to understand wether liver modifications are just a reaction to an unbalanced feeding or a true trophic pathology.